1. Field
The present disclosure pertains generally to audio signal processing, and more specifically, to near-field audio signal detection and noise suppression.
2. Background
Devices such as cellular phones, two-way radios and personal digital assistants (PDAs) that accept audio input are often used in adverse noise environments such as crowds, busy streets, restaurants, airports, vehicles or the like. Unwanted sounds generated from various sound sources within an audio environment, referred to as background noise, can emanate from differing locations within that audio environment. Common examples can include, but are not limited to, automobile noises or other voices within a crowded public place. Regardless of the source, the inability to distinguish a desired audio signal from background noise can result in audio input signals having decreased quality.
Strong background noise in these environments can obscure a user's speech and make it difficult to understand what the person is saying. In many cases, noise corrupts a speech signal and hence significantly degrades the quality of the desire audio signal. In cellular phones, for example, a person conversing in a noisy environment, like a crowded cafe or a busy train station, might not be able to converse properly as the noise corrupted speech perceived by a listener on the other end of a call is less intelligible. In all such cases of audio corruption, improving the quality of transmitted audio by suppressing background noise is desirable.
While noise filtering systems have been developed that attempt to remove background noise, these systems have not been able to remove all of the noise in all environments. Thus, there is a need for an improved technique of detecting and suppressing background noise.